In the field of displays, a liquid crystal display (LCD) has been widely used as an alternative to existing cathode ray tube-based displays. LCDs exhibit a tendency toward slimness, are lightweight, and a allow for a large display size, and with these tendencies, research into enhancing uniformity of displayed images, and contrast ratios or viewing angles of LCD display devices to realize higher picture quality have been continuously performed.
In general, an LCD comprises a color filter array substrate formed with a black matrix for preventing light leakage, and a color filter layer for realizing colorization, a thin film transistor (TFT) array substrate formed with thin film transistors and an electrode, and a liquid crystal cell interposed between the color filter array substrate and the TFT array substrate. These LCDs are classified into a twisted nematic LCD, a super twisted nematic LCD, a vertical alignment LCD, an in-plane switching mode LCD, etc. according to arrangements of liquid crystal molecules within the liquid crystal cell.
In such LCDs, since optical anisotropy of liquid crystal molecules in a liquid crystal cell allows a refractive index to vary with a viewing angle, thus changing picture color and brightness, a compensation film for compensating for such a change is used. At this time, since the optical anisotropy of the liquid crystal cell varies with the alignment of liquid crystal molecules, optical properties of the compensation film also vary with the mode of a liquid crystal cell.
To solve a viewing angle issue due to birefringence characteristics of liquid crystal molecules, a uniaxially or biaxially stretched TriAcetyl Cellulose (TAC) film or Cyclo-Olefin Polymer (COP) film has mainly been used as a related art compensation film. However, since optical characteristics (especially retardation characteristics) are determined according to basic birefringence of a raw material and a polymer chain orientation, there is a limitation on manufacturing a compensation film having desired optical characteristics from only existing films.
Therefore, there is a need to develop a new raw material to manufacture a compensation film having a more excellent characteristic.